The Memphis appeal. [volume] (Memphis, Tenn.) 1886-1890, 1887-01-22

cellent mech anical filtration. Her
mApy's Report, p. %, shows, however,
that much better results were OBJ
tanned by simple subsidence, es an
average OF but 800 grains colds per
gallon were found. OF course | know
the test was q severe one; but was it
more than the apparatus would be cub
acted tn at times in actual working2
Now, what becomes of the seventy
seven grains removed2 Tney we're
merely mechanically retarded, not chem
ically removed. Now, uDlees this re
tdrded matter is Uholly removed, by
washing or an equivalent device, it be-
con. es cumu alive, and the filter must
become eventually ineffective. The
washing device, mentioned by Mr..
Cross, may be complete in its action,
and II msy not; certainly the eff
cheney of the filter depends on this.
This Ia why l would liks evidence OF
it's continued effectiveness, not what it
NAV do under simple tests; especially
as DIR. Smsrl report shows that the
water was passed through a neUty
charged or httLe WOrked filter. | can fad
no evidences that the real effectiveness Of
He fter has been sstled. Tue reports OF
Messrs. Wilson and Gross are very
interesting to me, fIr they
are in field not unfamiliar.
l don't know Mr.. Wilson, but jndg-
ing from his report he is familiar with
machines, bat not with mechanical
principles. / can't quite understand
his approval Of devices "if properly de-
| ,innaJ Ifha a ,nr UNA ~ Hs,tirea no
approves OF details; for device 10 more
than q mechanical notion, 1t is de-
tailed mechanism. II he clearly under
stood the device, he knew, or ought to
have known, whether or not it was
properly designed. Ii locks little rs IL
he was giving an opinion on a ma
chine or plant hs did not clearly un-
derstand, or he would not have APP
proved OF device with an II. The
first device he Commends If IL is
properly designed" is that proposed
ior feeding the coagulant above the
filter bed fear il will be found no
boys task 10 design a wheel (turbine)
that shall do effective work against the
head that operates IL, "a l understand
that deyics is intended 70 do. 1t is a
well known principle in hydro-me-
chanics that the efficiency of a tur-
bine increases as the velocity Of en-
trance n w exceeds the velocity OF
exit flow through the wheel. II
there Is no difference the wheel does
no work. II the velocity OF the exit
Is zero, oil the energy OF the
stream goes into the wheel. Perhaps
the placing OF the wheel into a "by-
pass" is contem plated. Well, l would
like TO sac the detsils oil the apparatus
for supplying the coagulant. 1t is no
ticesble that Mr.. Cross m axes M COM
ment on this feature. Mr.. Wilson
commends, "if properly designed"
the device for seratiDg the water alter
filtration. do not believe 1t practi-
cable 10 "desigu properly" such q do
vice as Mr.. Wilson describes. IL IL
apparently the ''stesm mi sctor" princi-
pie attempted for other uses, Its uss
la blast furnaces and its use as the
filtering company propose to use 1t ara
very different. Field uses 1t properly
in his aush tank TO create vacuum
in the long leg of the siphon; but
doubt II it be advisable or even practi-
cable to apply it TO the aeration OF
water. The device is the well known
inverted 1phO4,, nothing more, nothing
less. The veocity Of a1w will be that
due to the difference OF level in the
two legs. certainly, in view OF the
elementary principles, can see no reason
to anticipate any great aeration with
this device. 30 much for the aeratine
apparatus view by Mr.. Wilison. But
Mr.. Or oss has something to say OF it.
From him We learu what was bs'
fore q mere inference, that the
device is expected b work under hedry
preaurei lila contsrhplated ~. plaee
the filters under fifteen feet Mead. =
!, emphatiCa'ly sgree with Mr.. Gross
that that is far too small a head, anC
think even fifty feet, which he recon
mends, Is too small II we assume
three feet OF the filter to be sand, the
,, other three to be coke and gravel, w
,, cauno. be far astiay in a computat on
Sand ne-quarter OF millimetre IL
! siEe Is not fue sand, bat a gooC
average To pass 0 "a Of gallon pc
second per square foot Che assumed
: duty OF the filter) through three fee
: OF su 1h sand would require a head o
fiity.one feet. ltreqnlres more to carr.
; il through the entire depth OF tn
. iitering media.
Ifthe ga ID is finer, or, what is praC
ticaliy the sam tn lug, II the interstice
: become clogyed, as they wia to som
. extent, still greater head wilt be re
! CURED. Mr.. Orosi is right when h
ssys the rate OF filtration Gained i
y i'm practicable under the head in
tended. These expert reports hav
;, put things in such light that We cal
. see, at least with fair d9gres OF AZ
= proxlm All on, what the.proposed plan
y must and can do. 1t is prop -sed ths
100000 gallo is be furnished pc
y diem. This il equivalent under con
. stani working to l4.6 cubic feet pc
. second, requiring a head oil abou
. fitly-thrse feet for overcoming iriC
, ton in nine mills Of Thirty inc
pipe. The surface Of the pre-
- posed reservoir is about ninety-fv
= feet above the river at source OF SUI
y ply. II think it rather more). s
70 the pumping machinery at the soutC
% must work against head OF not lei
i than 95 feet (static head) plus tif,y
!, seven feet otter head) plu
y fiity-three feet (frictien hesd) or q
q feet or So pounds-a pretty heav
= head for constant service, but not a
= excessive one. l am tempted to ent'
" into estim ates OF cost, operating e.
! psnsss, etc, bat you sec | would NJ
:, agree with the experts" There
= another thing l would epeak OF, an
that 10 the percentage OF water nesdt
y to wash (cleanse) the Fl tering medi
" Both Mr.. Wilson and Mr.. Cross plat
X the est per cent higher tbs
~ the fihering company does. 1t seen
to be guess work" with them all III
idea, or, rather, device, for washing
" one familiar to mining men In o
In concentration, and dsla obtainaol
n easily 30, would, or rather should, ha'
10 enabled the gen llemen TO make a ia
10 estimate. II ever have to enter up
ID an examination Of this plant l sni
'r. take tn 6 washing" expense as an II
II | .o.a..3 osn NJ. william il avidanf